The number of separated immigrant children is far greater than the amount revealed in a court-ordered review, according to a report released Thursday by the inspector general for the U.S. Department of Health and Human Services.

HHS has so far identified 2,737 children transferred to its care by immigration authorities in response to a court order in Ms. L v. Ice, the class action lawsuit that obtained family reunification.

But thousands of children might have been separated from their parents and guardians during an influx of immigrants that began in 2017 before the court-required accounting, the report says. The Washington Post, Politico, CNN and the New York Times have coverage.

The total number of separated families is unknown, the report revealed.

Nor is it known whether children have been reunified with families if they were separated during the 2017 influx, HHS Inspector General Ann Maxwell told Politico and other reporters in a press call.

The Department of Homeland Security separated the children from their families and transferred them to the Office of Refugee Resettlement, an office of HHS.

The IG’s report identifies several reasons why children haven’t been identified. The Department of Homeland Security has not provided detailed information about the children, and there isn’t an “integrated data system” to track children across agencies. There is also “complexity of determining which children should be considered separated.”

It is unclear whether recent changes to systems and processes will clear up the problems, according to the report. “The jury is still out on that,” Maxwell told the Washington Post.

More reports are planned, including reports on the children’s housing and health.

In the press call, Maxwell told reporters the current report doesn’t address whether senior Trump administration officials knew about the separations that occurred before an April 2018 announcement of a zero tolerance policy on illegal entry, according to Politico. “We did not, in this report, address who knew what, when,” Maxwell said.

The American Civil Liberties Union had filed the Ms. L lawsuit, which partly settled in September.

Lee Gelernt, lead attorney and deputy director of the ACLU’s Immigrants’ Rights Project, said in a statement Thursday: “We will be back in court over this latest revelation.”

“This policy was a cruel disaster from the start,” he said. “This report reaffirms that the government never had a clear picture of how many children it ripped from their parents.”